Standard armor for a tank, personnel carrier, mobile gun, or the like has been improved since the days of thick plating or built-up laminated plates. The major modern development is so-called active armor which contains an interference charge that explodes when hit by a projectile to destroy or deflect this projectile, thereby preventing it from penetrating.
As disclosed in commonly owned U.S. applications Nos. 213,171 and 295,551 a projectile for attacking multiple-layer, or active armor of an armored vehicle such as a tank, personnel carrier, or weapons carrier has a main device and an auxiliary device. These devices are generally similar in configuration and nature with the main device being larger than the auxiliary device and at least the auxiliary device forming an armor-piercing or -breaking unit. In such a projectile the point of the auxiliary device is effective on the target before that of the main device, facilitating the armor-piercing or -breaking effect. Normally the main device has an elongated impact or inertial projectile which works against the target substantially by impact, that is by transmitting its kinetic energy to the target. The secondary device can be similarly of the impact type.
In addition in this prior-art system the main device has a target-sensing device which accelerates the auxiliary projectile relative to the main projectile when the target is sensed. Thus the auxiliary projectile will strike the target first. This is achieved by forming the main projectile as a barrel-like tube receiving the secondary projectile and a charge for firing it from the main projectile.
Such an arrangement is highly effective. Nonetheless the central barrel-like passage of the main projectile substantially weakens this part, so that it occasionally breaks up even before impact. This can particularly happen when the propellant charge for the secondary projectile is somewhat too powerful, a problem when the active armor in question has been phlegmatized.